Mössbauer effect, d.c. magnetisation (temperature variation, irreversibility, hysteresis and field dependence), a.c. susceptibility and x-ray measurements in FeMnTiO5 (4.2 ≤ T <- 500 K) show it to be an anisotropic reentrant ferrimagnet where magnetic ordering and spin freezing occur only along the c-axis. This is a consequence of the f- and c- site chemical disorder, and orthorhombic c-axis distortion. © 1987 J.C. Baltzer A.G., Scientific Publishing Company.